diff --git a/makefile.lst b/makefile.lst
index e3e4ddc64..f5544bb5e 100644
--- a/makefile.lst
+++ b/makefile.lst
@@ -7,7 +7,6 @@ ASE = aseprite$(EXE)
 
 COMMON_SOURCES =					\
 	src/ase/context.cpp				\
-	src/ase/current_sprite.cpp			\
 	src/ase/ui_context.cpp				\
 	src/commands/cmd_about.cpp			\
 	src/commands/cmd_advanced_mode.cpp		\
diff --git a/src/ase_exception.h b/src/ase_exception.h
index 1e73dbeb7..a8ac0534e 100644
--- a/src/ase_exception.h
+++ b/src/ase_exception.h
@@ -39,6 +39,10 @@ public:
   {
   }
 
+  virtual ~ase_exception() throw()
+  {
+  }
+
   void show()
   {
     Console console;
diff --git a/src/commands/cmd_advanced_mode.cpp b/src/commands/cmd_advanced_mode.cpp
index 388058f95..e27dab391 100644
--- a/src/commands/cmd_advanced_mode.cpp
+++ b/src/commands/cmd_advanced_mode.cpp
@@ -56,7 +56,7 @@ static void cmd_advanced_mode_execute(const char *argument)
     char key[1024];
     char buf[1024];
 
-    JWidgetPtr window = load_widget("advanced.jid", "advanced_mode_warning");
+    JWidgetPtr window(load_widget("advanced.jid", "advanced_mode_warning"));
     JWidget warning_label = find_widget(window, "warning_label");
     JWidget donot_show = find_widget(window, "donot_show");
 
diff --git a/src/commands/cmd_canvas_size.cpp b/src/commands/cmd_canvas_size.cpp
index c671fb790..e66700d04 100644
--- a/src/commands/cmd_canvas_size.cpp
+++ b/src/commands/cmd_canvas_size.cpp
@@ -44,7 +44,7 @@ static void cmd_canvas_size_execute(const char *argument)
   CurrentSpriteWriter sprite;
 
   // load the window widget
-  JWidgetPtr window = load_widget("canvas.jid", "canvas_size");
+  JWidgetPtr window(load_widget("canvas.jid", "canvas_size"));
   get_widgets(window,
 	      "left", &left,
 	      "top", &top,
diff --git a/src/commands/cmd_cel_properties.cpp b/src/commands/cmd_cel_properties.cpp
index 4f29b5682..2e99874ec 100644
--- a/src/commands/cmd_cel_properties.cpp
+++ b/src/commands/cmd_cel_properties.cpp
@@ -62,7 +62,7 @@ static void cmd_cel_properties_execute(const char *argument)
   /* get current cel (can be NULL) */
   cel = layer_get_cel(layer, sprite->frame);
 
-  JWidgetPtr window = load_widget("celprop.jid", "cel_properties");
+  JWidgetPtr window(load_widget("celprop.jid", "cel_properties"));
   get_widgets(window,
 	      "frame", &label_frame,
 	      "pos", &label_pos,
diff --git a/src/commands/cmd_configure_screen.cpp b/src/commands/cmd_configure_screen.cpp
index 8998ed2ad..dac8e7268 100644
--- a/src/commands/cmd_configure_screen.cpp
+++ b/src/commands/cmd_configure_screen.cpp
@@ -77,7 +77,7 @@ static void show_dialog()
   JWidget resolution, color_depth, pixel_scale, fullscreen;
   char buf[512];
 
-  JWidgetPtr window = load_widget("confscr.jid", "configure_screen");
+  JWidgetPtr window(load_widget("confscr.jid", "configure_screen"));
   get_widgets(window,
 	      "resolution", &resolution,
 	      "color_depth", &color_depth,
@@ -133,10 +133,10 @@ static void show_dialog()
 
     /* setup graphics mode */
     if (try_new_gfx_mode()) {
-      JWidgetPtr alert_window = jalert_new("Confirm Screen"
-					   "<<Do you want to keep this screen resolution?"
-					   "<<In 10 seconds the screen will be restored."
-					   "||&Yes||&No");
+      JWidgetPtr alert_window(jalert_new("Confirm Screen"
+					 "<<Do you want to keep this screen resolution?"
+					 "<<In 10 seconds the screen will be restored."
+					 "||&Yes||&No"));
       jwidget_add_hook(alert_window, -1, alert_msg_proc, NULL);
 
       seconds_to_accept = 10;
diff --git a/src/commands/cmd_configure_tools.cpp b/src/commands/cmd_configure_tools.cpp
index 3e94b2fd1..ec6ac4417 100644
--- a/src/commands/cmd_configure_tools.cpp
+++ b/src/commands/cmd_configure_tools.cpp
@@ -73,9 +73,6 @@ static void cmd_configure_tools_execute(const char *argument)
 
   if (!window) {
     window = load_widget("toolconf.jid", "configure_tool");
-    if (!window)
-      return;
-
     first_time = TRUE;
   }
   /* if the window is opened, close it */
diff --git a/src/commands/cmd_duplicate_sprite.cpp b/src/commands/cmd_duplicate_sprite.cpp
index b67da6578..63da877c1 100644
--- a/src/commands/cmd_duplicate_sprite.cpp
+++ b/src/commands/cmd_duplicate_sprite.cpp
@@ -43,7 +43,7 @@ static void cmd_duplicate_sprite_execute(const char *argument)
   char buf[1024];
 
   /* load the window widget */
-  JWidgetPtr window = load_widget("dupspr.jid", "duplicate_sprite");
+  JWidgetPtr window(load_widget("dupspr.jid", "duplicate_sprite"));
 
   src_name = jwidget_find_name(window, "src_name");
   dst_name = jwidget_find_name(window, "dst_name");
diff --git a/src/commands/cmd_frame_properties.cpp b/src/commands/cmd_frame_properties.cpp
index 66142e8f4..d91f19f7f 100644
--- a/src/commands/cmd_frame_properties.cpp
+++ b/src/commands/cmd_frame_properties.cpp
@@ -48,7 +48,7 @@ void dialogs_frame_length(const SpriteReader& sprite, int sprite_frame)
   JWidget frame, frlen, ok;
   char buf[64];
 
-  JWidgetPtr window = load_widget("frlen.jid", "frame_duration");
+  JWidgetPtr window(load_widget("frlen.jid", "frame_duration"));
   get_widgets(window,
 	      "frame", &frame,
 	      "frlen", &frlen,
diff --git a/src/commands/cmd_layer_properties.cpp b/src/commands/cmd_layer_properties.cpp
index 1efc2e2da..80a57023b 100644
--- a/src/commands/cmd_layer_properties.cpp
+++ b/src/commands/cmd_layer_properties.cpp
@@ -42,7 +42,7 @@ static void cmd_layer_properties_execute(const char *argument)
   CurrentSpriteWriter sprite;
   Layer *layer = sprite->layer;
 
-  JWidgetPtr window = jwindow_new(_("Layer Properties"));
+  JWidgetPtr window(jwindow_new(_("Layer Properties")));
   box1 = jbox_new(JI_VERTICAL);
   box2 = jbox_new(JI_HORIZONTAL);
   box3 = jbox_new(JI_HORIZONTAL + JI_HOMOGENEOUS);
diff --git a/src/commands/cmd_new_file.cpp b/src/commands/cmd_new_file.cpp
index 24f758b6a..bd5b6d8f2 100644
--- a/src/commands/cmd_new_file.cpp
+++ b/src/commands/cmd_new_file.cpp
@@ -62,7 +62,7 @@ static void cmd_new_file_execute(const char *argument)
   };
 
   /* load the window widget */
-  JWidgetPtr window = load_widget("newspr.jid", "new_sprite");
+  JWidgetPtr window(load_widget("newspr.jid", "new_sprite"));
 
   width = jwidget_find_name(window, "width");
   height = jwidget_find_name(window, "height");
diff --git a/src/commands/cmd_new_layer.cpp b/src/commands/cmd_new_layer.cpp
index e85084c96..7e8dfb186 100644
--- a/src/commands/cmd_new_layer.cpp
+++ b/src/commands/cmd_new_layer.cpp
@@ -41,7 +41,7 @@ static void cmd_new_layer_execute(const char* argument)
 {
   CurrentSpriteWriter sprite;
 
-  JWidgetPtr window = load_widget("newlay.jid", "new_layer");
+  JWidgetPtr window(load_widget("newlay.jid", "new_layer"));
   JWidget name_widget = find_widget(window, "name");
   {
     char* name = get_unique_layer_name(sprite);
diff --git a/src/commands/cmd_new_layer_set.cpp b/src/commands/cmd_new_layer_set.cpp
index 23e61f9df..28eea4ef3 100644
--- a/src/commands/cmd_new_layer_set.cpp
+++ b/src/commands/cmd_new_layer_set.cpp
@@ -39,7 +39,7 @@ static void cmd_new_layer_set_execute(const char *argument)
   CurrentSpriteWriter sprite;
 
   // load the window widget
-  JWidgetPtr window = load_widget("newlay.jid", "new_layer_set");
+  JWidgetPtr window(load_widget("newlay.jid", "new_layer_set"));
 
   jwindow_open_fg(window);
 
diff --git a/src/commands/cmd_palette_editor.cpp b/src/commands/cmd_palette_editor.cpp
index 107370290..21216863a 100644
--- a/src/commands/cmd_palette_editor.cpp
+++ b/src/commands/cmd_palette_editor.cpp
@@ -87,7 +87,7 @@ static void cmd_palette_editor_execute(const char *argument)
   }
 
   /* load widgets */
-  JWidgetPtr window = load_widget("paledit.jid", "palette_editor");
+  JWidgetPtr window(load_widget("paledit.jid", "palette_editor"));
   get_widgets(window,
 	      "red", &slider_R,
 	      "green", &slider_G,
diff --git a/src/commands/cmd_sprite_properties.cpp b/src/commands/cmd_sprite_properties.cpp
index 5e31ccb44..55ccd9982 100644
--- a/src/commands/cmd_sprite_properties.cpp
+++ b/src/commands/cmd_sprite_properties.cpp
@@ -49,7 +49,7 @@ static void cmd_sprite_properties_execute(const char *argument)
   char buf[256];
 
   /* load the window widget */
-  JWidgetPtr window = load_widget("sprprop.jid", "sprite_properties");
+  JWidgetPtr window(load_widget("sprprop.jid", "sprite_properties"));
   get_widgets(window,
 	      "name", &name,
 	      "type", &type,
diff --git a/src/commands/cmd_sprite_size.cpp b/src/commands/cmd_sprite_size.cpp
index 2797bd245..9fc1c30b6 100644
--- a/src/commands/cmd_sprite_size.cpp
+++ b/src/commands/cmd_sprite_size.cpp
@@ -137,7 +137,7 @@ static void cmd_sprite_size_execute(const char *argument)
   const CurrentSpriteReader sprite;
 
   // load the window widget
-  JWidgetPtr window = load_widget("sprsize.jid", "sprite_size");
+  JWidgetPtr window(load_widget("sprsize.jid", "sprite_size"));
   get_widgets(window,
 	      "width_px", &width_px,
 	      "height_px", &height_px,
diff --git a/src/commands/fx/cmd_color_curve.cpp b/src/commands/fx/cmd_color_curve.cpp
index 546dbfa3b..aef1226b2 100644
--- a/src/commands/fx/cmd_color_curve.cpp
+++ b/src/commands/fx/cmd_color_curve.cpp
@@ -70,7 +70,7 @@ static void cmd_color_curve_execute(const char *argument)
 		 the_curve);
   }
 
-  JWidgetPtr window = load_widget("colcurv.jid", "color_curve");
+  JWidgetPtr window(load_widget("colcurv.jid", "color_curve"));
   get_widgets(window,
 	      "preview", &check_preview,
 	      "button_ok", &button_ok,
diff --git a/src/commands/fx/cmd_convolution_matrix.cpp b/src/commands/fx/cmd_convolution_matrix.cpp
index 4bcedaf1b..a344e0201 100644
--- a/src/commands/fx/cmd_convolution_matrix.cpp
+++ b/src/commands/fx/cmd_convolution_matrix.cpp
@@ -82,7 +82,7 @@ static void cmd_convolution_matrix_execute(const char *argument)
   JWidget box_target;
   JWidget reload, generate;
 
-  JWidgetPtr window = load_widget("convmatr.jid", "convolution_matrix");
+  JWidgetPtr window(load_widget("convmatr.jid", "convolution_matrix"));
   get_widgets(window,
 	      "preview", &check_preview,
 	      "tiled", &check_tiled,
@@ -221,7 +221,7 @@ static bool generate_select_hook(JWidget widget, void *data)
   JWidget div, div_auto;
   JWidget bias, bias_auto;
 
-  JWidgetPtr window = load_widget("convmatr.jid", "generate_convolution_matrix");
+  JWidgetPtr window(load_widget("convmatr.jid", "generate_convolution_matrix"));
   get_widgets(window,
 	      "view_x", &view_x,
 	      "view_y", &view_y,
diff --git a/src/commands/fx/cmd_despeckle.cpp b/src/commands/fx/cmd_despeckle.cpp
index 35662ebe6..96e9445ad 100644
--- a/src/commands/fx/cmd_despeckle.cpp
+++ b/src/commands/fx/cmd_despeckle.cpp
@@ -67,7 +67,7 @@ static void cmd_despeckle_execute(const char *argument)
   JWidget box_target, target_button, button_ok;
   char buf[32];
 
-  JWidgetPtr window = load_widget("median.jid", "median");
+  JWidgetPtr window(load_widget("median.jid", "median"));
   get_widgets(window,
 	      "width", &entry_width,
 	      "height", &entry_height,
diff --git a/src/commands/fx/cmd_invert_color.cpp b/src/commands/fx/cmd_invert_color.cpp
index 7bb6838a5..17c3f2b27 100644
--- a/src/commands/fx/cmd_invert_color.cpp
+++ b/src/commands/fx/cmd_invert_color.cpp
@@ -61,7 +61,7 @@ static void cmd_invert_color_execute(const char *argument)
   JWidget box_target, target_button, button_ok;
   const CurrentSpriteReader sprite;
 
-  JWidgetPtr window = load_widget("invrtcol.jid", "invert_color");
+  JWidgetPtr window(load_widget("invrtcol.jid", "invert_color"));
   get_widgets(window,
 	      "target", &box_target,
 	      "preview", &check_preview,
diff --git a/src/commands/fx/cmd_replace_color.cpp b/src/commands/fx/cmd_replace_color.cpp
index 2da5b7b3b..9f498b8a1 100644
--- a/src/commands/fx/cmd_replace_color.cpp
+++ b/src/commands/fx/cmd_replace_color.cpp
@@ -66,7 +66,7 @@ static void cmd_replace_color_execute(const char *argument)
   JWidget box_target, target_button;
   JWidget button_ok;
 
-  JWidgetPtr window = load_widget("replcol.jid", "replace_color");
+  JWidgetPtr window(load_widget("replcol.jid", "replace_color"));
   get_widgets(window,
 	      "color_buttons_box", &color_buttons_box,
 	      "preview", &check_preview,
diff --git a/src/dialogs/options.cpp b/src/dialogs/options.cpp
index 2584645a0..d33f9bc3a 100644
--- a/src/dialogs/options.cpp
+++ b/src/dialogs/options.cpp
@@ -60,7 +60,7 @@ void dialogs_options()
   old_y = y;
 
   /* load the window widget */
-  JWidgetPtr window = load_widget("options.jid", "options");
+  JWidgetPtr window(load_widget("options.jid", "options"));
   get_widgets(window,
 	      "mouse_x", &slider_x,
 	      "mouse_y", &slider_y,
diff --git a/src/file/jpeg_format.cpp b/src/file/jpeg_format.cpp
index af6589300..50869799d 100644
--- a/src/file/jpeg_format.cpp
+++ b/src/file/jpeg_format.cpp
@@ -360,7 +360,7 @@ static FormatOptions *get_options_JPEG(FileOp *fop)
       return (FormatOptions*)jpeg_options;
 
     /* widgets */
-    JWidgetPtr window = load_widget("jpeg_options.jid", "jpeg_options");
+    JWidgetPtr window(load_widget("jpeg_options.jid", "jpeg_options"));
     JWidget slider_quality, ok;
     get_widgets(window,
 		"quality", &slider_quality,
diff --git a/src/main.cpp b/src/main.cpp
index e70f86da3..e555612eb 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -37,13 +37,13 @@ public:
   ~Allegro() { allegro_exit(); }
 };
 
+#if defined MEMLEAK
 class MemLeaks {
 public:
-#if defined MEMLEAK
   MemLeaks() { jmemleak_init(); }
   ~MemLeaks() { jmemleak_exit(); }
-#endif
 };
+#endif
 
 //////////////////////////////////////////////////////////////////////
 //			       Main Routine
@@ -52,7 +52,9 @@ public:
 int main(int argc, char *argv[])
 {
   Allegro allegro;
+#if defined MEMLEAK
   MemLeaks memleaks;
+#endif
 
   set_uformat(U_ASCII);
 
diff --git a/src/modules/gui.h b/src/modules/gui.h
index 47580a9aa..29fb7df74 100644
--- a/src/modules/gui.h
+++ b/src/modules/gui.h
@@ -23,6 +23,7 @@
 #include <string>
 #include "ase_exception.h"
 #include "jinete/jbase.h"
+#include "jinete/jwidget.h"
 
 //////////////////////////////////////////////////////////////////////
 
@@ -115,7 +116,7 @@ public:
     m_widget = NULL;
   }
 
-  JWidgetPtr(JWidget widget) {
+  explicit JWidgetPtr(JWidget widget) {
     m_widget = widget;
   }